Studies of the specificity and efficiency of reactions catalyzed by enzymes and the elucidation of a biological control mechanism are the particular subjects of this proposal. We plan to investigate the contributions which may be made to the efficiency of enzyme-catalyzed reactions by the stabilization of reactive intermediates in the enzyme-substrate complex. We also plan to continue our investigations of a mechanism for biological control involving conformational changes of a protein, which has a central function in electron transport. We plan to use Raman laser spectroscopy to obtain information about the crystalline enzyme-substrate complex and flow and relaxation methods to obtain information about enzyme-substrate complex formation in solution. The enzymes chosen are of interest to health-related problems. The serine proteases include enzymes involved in blood clotting, nerve transmission, and digestive processes. Some of these enzymes are used clinically in the treatment of inflammations. A possible role in cancer therapy has recently been suggested for lysozyme, an important enzyme in biological defence mechanisms.